Pin-anchor escapement for timepieces



T. TODA.

PIN ANCHOR ESOAPEIIENT FOR TIIIEHECES.

APPLICATION FILED u0v 14. me.

1,343,798. PatentedJune 15, 1920.

UNITED STATES PATENT OFFICE.

TOMOKICHI TODA, OF KAIJO, CHOSEN, ASSIGNOR 0F ONE-HALF T0 TOMOKICHITAKATA, 0F NAGOYA CITY, JAPAN, AND

OFIWATE, JAPAN.

ONE-HALF T0 HANSUKE GUNJI,

PIN-ANCHOR ESCAPEMENT FOR 'IIMEPIECES.

Specification of Letters Patent. Patented J e 15, 1920,

Application filed November 14, 1918. Serial No. 262,627.

To all whom it may concern Be it known that I, TOMOKIGHI ToDA, a subjectof the Emperor of Japan, and resident of 116 Kitahommachi, Kaijo, KeikiDo, Chosen, Empire of Japan, have invented certain new and usefulImprovements in Pin-Anchor Escapements for Timepieces, of which thefollowing is a specification.

My invention relates to an improvement in the so-called pin-anchorescapement hitherto in use, wherein a lever known as an anchor isarranged adjacent to an escapement-wheel tending to rotate in a definitedirection through the force of a winding spring and the catching andreleasing of the escapement-wheel are performed alternately inaccordance with the oscillation of the said lever by means of pinsfitted to the arm of the lever, and consists in providing twogear-wheels, instead of one as has been the case hitherto, and in makingspecial arrangements accordingly toattain the objects in View, each ofthe said gear-wheels being provided with teeth so constructed that theside of each tooth facing the direction of rotation is curved into anarc-shape to conform with the path of oscillation of a particularengaging pin, and a pin being fitted to each of the two arms of theanchor to engage with a corresponding gear wheel.

The prime object of my invention is to provide an improved pin-anchorescapement capable of absolutely eliminating recoils'of the gearwvheel,incident to pin-anchor escapements hitherto in existence, making theescaping action smooth, maintaining constant moving conditionsirrespective of the strength of the winding spring, and increasingdurability of running of the mechanism.

Other objects and advantages to be derived from the use of my inventionwillappear in the following detailed description and the claims, takenwith an inspection of the accompanying drawings, in which:

Figure 1 is a side elevational view of the pin-anchor escapementembodying my invention; Fig. 2 is a front elevational view of theprincipal parts thereof; and, Figs. 3 and 4 are, respectively, magnifiedviews of part of the same, showing the manner of escape action.

Throughout the several views, similar characters for reference designatelike and corresponding parts.

An axle 2 is mounted on a framework 1l, front and rear gear-wheels 3 and1 are attached to the axle 2, an axle '5 is arranged above the same, alever or the so-called anchor 6 is rigidly fixed in a positionintermediate the said two gear-wheels, pins 7 and 8 are provided at thetwo opposite ends of the lever so as to act on the gear-Wheels 3 and 4,respectively, an arm 9 with its farther end forked is attached to theaxle 5 to face on a disk 12 fitted to the axle 11 of a balance 10, and ahair-spring 13 is arranged on the head of the axle 11, all these partsbeing so arranged and constructed that the forked end of the arm 9presses a pin 14 provided on the disk 1% and turns the balance 10 whenthe said arm oscillates, and energy or force stored in the hair-spring13 reverses the same, which makes it possible to maintain periodicallyreciprocating rotations of the balance. The arm 9 is limited in itsmovement by pins 15 and 15 firmly set on the framework, and a pin 16attached to the farther end is made to come into contact with theperiphery of the disk 12 to prevent its unnecessary motion and to allowthe arm to oscillate only when it has engaged with a groove or notch 17provided at part of the disk.

The axle 2 of the gear-wheels 3 and 4 is connected with the windingspring of the timepiece mechanism by means of any suitable toothedgearing and possesses escaping force tending to rotate clockwise at alltimes, and alternately catches and releases the teeth of the gear-wheels3 and 1 through the pins 7 and 8 and advances or rotates themintermittently by one tooth at a time. And whenv the gear-wheels 3 andat rotate, the slant side provided at the end of each tooth presses thepins 7 and 8 and imparts oscillation to the lever 6 and moves thebalance or the pendulum as is usually the case with an ordinarytimepiece mechanism. In

my invention, each of the teeth of the gearwheel 3 has its side facingthe direction of rotation. that is, its right side, curved into anarc-shape to conform with the path of oscillation of the engaging pinwith, and each of the teeth of the gear-wheel e has its right sidecurved likewise with relation to the engaging pin, differing only in thepositions or directions of the curved sides, they being dianietrical,and this constitutes the main feature of my present invention. Todescribe this feature more fully:

In Fig. 3, each of the teeth 3, of the rear gear-wheel 3 correspondingto the left-hand pin 7 has its right side a-a arc-shaped, tending toincrease in width toward the root or base, conforming with a circularare described with the axle 5 as center and with the length of the armextending from the said axle to the outer periphery of the pin 7 asradius. And as shown in Fig. at, each of the teeth a of the frontgear-wheel 4: corresponding to the right-hand pin 8 has its right side5-?) arc-shaped, tending to decrease in width toward its root or base,conforming with a circular are described with the axle 5 as center andwith the length of the arm extending from the said axle to the pin 8 asradius. Fig. 3 shows the manner in which one of the teeth 3, is receivedby the left-hand pin 7, and in this case the pin 7 will slide along theright side a-a of the tooth 8, as the lever 6 oscillates clockwise, butthen the side ([/CL is so shaped as to conform with an are describedwith the axle 5 as center and the arm 5-7 as radius, so that thegear-wheel will. remain in rest in spite of the oscillation of the pin;and, at the moment when the pin finally gets out of engagement with theside (e-a the other pin 8 intervenes between the two teeth a, and 4%,thus releasing the gear-wheel for an instant and advancing or rotatingit by one tooth through the action of the winding spring, and the upperside a-c of the tooth 3, presses the pin 7 and imparts rotation to thelever G. And as soon as the pin 7 has got out of engagement with theextremity of the upper side 0 of the tooth 3 owing ,to change indeclination of the lever G, as

shown in Fig. 4t, the other pin 8 is received by the right side 7)Z) ofthe tooth 4 of the gear-wheel 1-, and since this side, too, is so shapedas to conform with an are described with the axle 5 as center and thearm 5-8 as radius, the gear-wheel a can remain in absolute rest in spiteof any oscillation of the lever while the said side is in contact withthe pin, and at the moment when the pin 8 has left the right side of thetooth 4t and shifted to the upper'slant side Z)-cl while the lever 6 isoscillating counter-clock wise, the gear-wheel is released and advancedor rotated, and then the left-hand pin 7 receives the succeeding tooth3,, and so .011, thus making it possible to advance or rotate thegear-wheels periodically and intermittently without the slightest recoilduring the rest.

In pin-anchor escapements known hitherto, a single escapement-wheel hasbeen used and so constructed as to cause two anchorpins, front and rear,to act on the same, and so the front side of each tooth has generallybeen shaped rectilinearly according to the direction of the radius, withthe consequence that the shape of the said side of the tooth cannotclosely conform with the path of oscillation of a lever, and producestendency to push the wheel more or less in an opposite direction indefiance to the action of the winding spring; in other words, theso-called recoil cannot be avoided with such forms of pin-anchoreseapements. And, if such recoil is produced at each movement of theescapement, it will not only consume the energy or force of the springand impairs durability of running of the timepiece, but also will tendto make the timepiece incorrect in its function of indicating time bycausing great difference in escaping actions according to the strengthof the winding spring. On the contrary, in my invention twoescapement-wheels are used instead of one to eliminate these defects,and the front side of each of the gear-wheels has been so shaped, as toconform with the path of oscillation of the engaging pin with, and sothere is no possibility of producing any recoil during the period ofrest, thus making it possible to run the same smoothly, keep time verycorrectly, and increase durability of the mechanism.

Having thus fully described my invention, what I claim as new and desireto secure by Letters Patent is:

1. A pin anchor escapement for time pieces including escapement wheelsprovided with teeth,.a pallet mounted adjacent each of the wheels forperiodically stopping and releasing the wheels, and arcuate edges on theteeth of the escapement wheels described from a point coincident withthe axis of rotation of the pallet to prevent recoil of the escapement.

2. A pin anchor escapement for time pieces including escapement wheelsprovided with teeth, a pallet mounted adjacent each of the wheels forperiodically stopping and releasing the wheels, and oppositely curvedarcuate edges on the teeth of each of the escapement wheels describedfrom a point coincident with the axis of rotation of the pallet toprevent recoil of the es- :a-pement.

3. A pin anchor escapement for time pieces including escapement wheelsprovided with teeth, a pallet mounted adjacent each of the wheels,arcuate edges on the teeth of one of the escapementwheels deaxis ofrotation of the pallet and of a curva- 1,34s,79s. a

scribed from a point coincident with the "and means on the pallet foralternately enaxis of rotation of the pallet, arcuate edges gaging theteeth on each of the escapement on the teeth of the other of the wheelsdewheels whereby to periodically stop and re- 10 scribed from a pointcoincident with the lease the Wheels Without recoil.

In testimony whereof I afiix my signature ture opposed to the curvatureof the arcuate hereto.

edges of the teeth of the first named wheel, TOMOKIGHI TODA.

